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Research Project: Methyl Bromide Replacement: Mitigation of the Invasive Pest Threat from the American Tropics and Subtropics

Location: Subtropical Horticulture Research

2017 Annual Report

1. Identify semiochemicals that mediate the behavior and physiology of exotic insects such as tephritid (Ceratitis and Anastrepha) and drosophilid (Zaprionus indianus) fruit flies, the redbay ambrosia beetle, the cocoa pod borer, and other new invasive pests from the Caribbean and Central and South America. 1.A. Determine and document behavioral and olfactory responses to semiochemicals that have potential use in monitoring and control systems. 1.B. Identify and quantify insect semiochemicals; develop improved systems to collect and identify semiochemicals. 2. Develop semiochemical- and/or chemical-based technologies that lead to products for detection, behavioral disruption, or surveillance of insect pests that threaten food security. 2.A. Develop synthetic and natural product lures based on host location and/or feeding cues that are formulated for effective use in integrated pest management. 2.B. Develop optimized trapping and control systems based on chemical lures in combination with traps and bait stations. 3. Develop practical systems for integrated pest management using semiochemical and other detection-based technologies to reduce the threat of importation and establishment of exotic pests from foreign tropical and subtropical environments by suppressing and/or controlling the population at the source. 3.A. Develop IPM tools for tephritid fruit flies using semiochemical-based technologies for use by regulatory agencies and growers; develop new approaches including improved protocols and spatial analysis techniques to assess monitoring approaches and control systems such as attract-and-kill technologies 3.B. To complement traditional breeding programs for plants resistant to R. lauricola, identify RAB resistant varieties that are low in RAB attractants and integrate quantitative semiochemical phenotype with genotype for marker-assisted selection of pest resistant plants to complement traditional breeding programs.

Research will consist of field and laboratory experiments to determine the behavior, physiology and chemical ecology of insect pests that can be used in the development of control techniques. Strategies will include the developing new detection and delimitation tools, baits and discrete attract-and-kill devices; identifying pest resistant plant varieties that are low in insect attractant chemicals; and discovering components in the insect's biology that can be exploited for formation of control measures for exotic insect pests that affect plant production.

Progress Report
Evaluation of Mexican Lauraceae for susceptibility to attack by redbay ambrosia beetle (RAB). All known hosts of RAB in the U.S. are trees in the family Lauraceae. Since its introduction into Georgia in 2002, RAB has invaded 8 additional states in the Southeast, including recent establishments in Texas and Arkansas. As its range continues to expand, RAB will most likely enter into Mexico, a country rich in species of Lauraceae. In collaboration with the Instituto de Ecología (Veracruz, Mexico), native Mexican laurels were evaluated for susceptibility to RAB attack. In addition, Hass avocado–the major cultivar grown in Mexico and California–was assessed for risk of RAB attack. Field tests and laboratory bioassays have been completed in Florida to determine relative attraction and boring preferences of RAB for these potential new hosts. Gas chromatography–mass spectrometry (GS-MS) analysis of volatile emissions from wood samples is in progress to identify chemical constituents in common with U.S. laurels. This information will be used to prepare a risk assessment for the Lauraceae of Mexico (8 natives and Hass avocado) and to identify potential new attractants to incorporate into lures for improved RAB detection, relating to Objective 1. Documenting differences in ambrosia beetle communities in forest and agricultural ecosystems with laurel wilt. RAB and laurel wilt are currently established in 9 southeastern states, which has resulted in severe mortality of native Persea (P.) species, including redbay (P. borbonia), swampbay (P. palustris), and silkbay (P. humilis). Laurel wilt now impacts production of avocado (P. americana) in south Florida, but in contrast to the situation in forests, RAB is detected at very low levels in affected groves. There is evidence that avocado is a poor reproductive host for RAB and that other ambrosia beetles may transmit the laurel wilt pathogen. To compare the dynamics in different ecosystems with laurel wilt, parallel field tests were conducted in an avocado grove (Miami-Dade Co., Florida) and a swampbay forest (Highlands Co., Florida). Tests used ethanol lures (the best general attractant for ambrosia beetles) and essential oil lures (the best attractants for RAB). Data are being collected on the diversity of beetles found at the two sites, as well as the species which can reproduce successfully on the two hosts. In collaboration with the University of Florida, fungal symbionts are also being analyzed to determine which beetles can function as vectors of laurel wilt. This research relates to Objective 3, development of methods to suppress and control pest populations. This information will aid in our understanding of the complex host-vector-pathogen interactions underlying the epidemiology of laurel wilt disease, and assist in development of integrated pest management (IPM) programs for disease vector(s). Comparison of the 50% copaene lure to other available RAB lures and lure combinations. Previous ARS research (Miami, Florida) led to development of an essential oil lure enriched to contain 50% a-copaene. In field trials, the copaene lure was found to be more attractive to RAB than the standard cubeb oil lure (both produced by Synergy Semiochemicals Corp., British Columbia, Canada). Further evaluations were conducted to compare efficacy and longevity of the new copaene lure to other commercially available RAB lures, including manuka oil, cubeb oil, and copaiba oil lures obtained from ChemTica USA (Durant, Oklahoma). In separate field tests, multicomponent lures were evaluated, including combinations of essential oils and eucalyptol (a monoterpene reported as a new RAB attractant)and essential oils and volatile spiroketals (fungal odors known to be attractive to other ambrosia beetles). Field tests have been completed and manuscripts are in preparation. This research relates to Objective 2, development of new lures for invasive insects. Results from this research will identify the most effective lure or lure combinations available for use by action agencies in detection programs for RAB. Evaluation of field life, chemical emissions, and sampling range of a two-component lure for pest Euwallacea. Recent ARS research in Miami, Florida, resulted in development of an improved detection system for pest Euwallacea ambrosia beetles in Florida avocado groves. This pest detection relies on baiting traps with two bubble lures–one containing an essential oil enriched in a-copaene (an attractive host odor) and the other containing quercivorol (an attractive fungal odor). Several 12-week field tests are underway to determine the longevity of attraction for these two lures, deployed separately and in combination. Concurrently, chemical sampling and analysis is being done on field-aged lures to quantify their volatile emissions, which will be correlated with the field captures. In addition, release-and-recapture experiments with marked beetles are being conducted to determine the sampling range (attractive distance) of the two lures, deployed alone and in tandem. This research relates to Objective 2 (development of new lures) and to Objective 3 (use of spatial analysis to assess monitoring approaches). Field test of new protein-based attractants for Caribbean fruit fly. Several protein-based attractants are under development but have not yet been tested for effectiveness for the Caribbean fruit fly. Therefore field tests were conducted in south Florida to evaluate a new liquid protein bait and a new type of synthetic lure based on chemicals emitted from protein baits, to compare capture by these baits with those currently used in fruit fly programs and also to determine longevity of the baits over time. This research relates to Objective 1, identification of new attractants for pest fruit flies and Objective 2, development of new lures for invasive insects. Results from this research will be used to develop improved attractants needed for this pest. Identification of kairomones from essential oils for male Mediterranean fruit fly. The standard synthetic attractant for male Mediterranean fruit flies is not as effective for either monitoring or control as male-targeted attractants for other pest fruit flies. Essential oils were the original source of male targeted attractants and may provide sources of improved lures. A new bioassay-guided fractionation and isolation process is being developed that will be used to identify additional kairomones. This research relates to Objective 3, development of methods to suppress and control pest populations. Results from this research will be used to identify additional chemicals that could be used to improve effectiveness of the standard male attractant for monitoring and potential control of this pest. Identification of chemical compounds from host fruit that are used as kairomones for Cocoa pod borer. Chemicals from host fruit are used by females to both find and accept host fruit. Extracts of plant tissues (endocarp, exocarp, pulp, seeds, flowers) from cacao were obtained and analyzed chemically, and were sent for laboratory and field tests in collaborator facilities in Indonesia to determine behavioral effects. This research relates to Objective 1, identification of attractants for exotic pests including the cocoa pod borer. Results from this research will be used to develop attractants needed for monitoring and controlling this pest. Identification of insect semiochemicals from tropical and subtropical plants. Plant material has long been recognized as a diverse and rich source of essential oils. Plants produce different classes of secondary metabolites and every plant has its own characteristic chemical profile. Research is ongoing to develop methods for identification of plant material at the ARS Miami station using a variety of extraction and analytical techniques. A library of chemicals emitted from plant-based material is being developed, which will facilitate component identification and quantification. This research relates to Objective 1, identification of new attractants for exotic insect pests.

1. Development of a two-component lure for better detection of pest Euwallacea ambrosia beetles. The tea shot hole borer, TSHB, (Euwallacea fornicatus) is a pest of commercial tea in Asia. Recently, several species of ambrosia beetle morphologically similar to TSHB have become established as pests in Israel, California, and Florida. Collectively referred to as E. near fornicatus, beetles within this cryptic species complex vector Fusarium spp. fungi which cause dieback disease in host trees, including avocado and other trees within the U.S. The situation is particularly serious in southern California, where avocado and many native species are severely impacted by Fusarium dieback. ARS scientists in Miami, Florida, discovered that a-copaene is a new attractant for E. nr. fornicatus. Copaene is equal in attraction to quercivorol (the current lure for this pest), but a combination of the two chemicals is synergistic, significantly increasing beetle captures. In collaboration with the University of Florida and Florida avocado growers, the new two-component lure is currently being used to survey the avocado production area of Miami-Dade County to determine the prevalence of this new ambrosia beetle pest.

Review Publications
Kendra, P.E., Montgomery, W.S., Schnell, E.Q., Deyrup, M., Epsky, N.D. 2016. Efficacy of a-copaene, cubeb, and eucalyptol lures for detection of redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae). Journal of Economic Entomology. 109(6):2428-2435.
Carrillo, D., Cruz, L.F., Kendra, P.E., Narvaez, T.I., Montgomery, W.S., Monterroso, A., Degrave, C., Cooperband, M.F. 2016. Ditribution, pest status and fungal associates of Euwallacea nr. fornicatus in Florda avocado groves. Insects. 7(4):55.
Ploetz, R.C., Konkol, J.L., Duncan, R.E., Saucedo, R.J., Campbell, A., Mantilla, J., Kendra, P.E., Carrillo, D. 2017. Presence and prevalence of Raffaelea lauricola, cause of laurel wilt, in different species of ambrosia beetle in Florida USA. Journal of Economic Entomology. 110(2):347-354.
Blythe, E.K., Demirci, B., Fatih, G., Tabanca, N. 2017. Characterization of volatile and polar compounds of Jiaogulan Tea [Gynostemma pentaphyllum (Thunb.) Makino] by hyphenated analytical techniques. Asian Journal of Chemistry. 29:1285-1290. doi:10.14233/ajchem.2017.20467.
Ploetz, R.C., Kendra, P.E., Chaundry, R.A., Rollins, J., Campbell, A.S., Hughes, M., Dreaden, T. 2017. Laurel wilt in natural and agricultural ecosystems: Understanding the drivers and scales of complex pathosystems. Forests. 8(2):48.
Ploetz, R.C., Hughes, M.A., Kendra, P.E., Fraedrich, S.W., Carrillo, D., Stelinski, L.L., Hulcr, J., Mayfield, A.E., Dreaden, T.J., Crane, J.H. 2017. Recovery plan for laurel wilt of avocado, caused by Raffaelea lauricola. Plant Health Progress. 18(2):51-77.
Niogret, J., Epsky, N.D., Gill, M.A., Espinoza, H.R., Kendra, P.E., Heath, R. 2017. Attraction and electroantennographic responses of male mediterranean fruit fly (diptera: tephritidae) to six plant essential oils. Journal of Entomology and Zoology Studies. 5(3):958-964.
Kendra, P.E., Owens, D., Montgomery, W.S., Narvaez, T.I., Bauchan, G.R., Schnell, E.Q., Tabanca, N., Carrillo, D. 2017. a-Copaene is an attractant, synergistic with quercivorol, for improved detection of Euwallacea nr. fornicatus (Coleoptera: Curculionidae: Scolytinae). PLoS One. 12(6):e0179416.
Epsky, N.D., Gill, M.A. 2017. Laboratory and field age of aqueous grape juice bait and capture of Zaprionus indianus (Diptera: Drosophilidae). Journal of Economic Entomology. 110(3):1326–1332.
Campbell, A., Ploetz, R., Dreaden, T., Kendra, P.E., Montgomery, W.S. 2016. Geographic variation in mycangial communities of Xyleborus glabratus. Mycologia. 108(4):657-667.
Guillen, L., Epsky, N.D., Kendra, P.E., Montgomery, W.S., Gill, M.A., Allen, C.L., Niogret, J., Heath, B. 2016. Electroantennogram response and attraction of Anastrepha suspensa to volatiles of various sugar sources and aged sugar solutions. Entomologia Experimentalis et Applicata. 160(3):251-258. doi:10.1111/eea.12483.
Aghraz, A., Wanner, J., Schmidt, E., Ait Dra, L., Ait Sidibrahim, M., Tabanca, N., Abbas, A., Nafis, A., Hassani, L., Markouk, M., Jirovetz, L., Larhsini, M. 2017. Chemical composition, in vitro antioxidant, antimicrobial and insecticidal activities of essential oil from Cladanthus arabicus. Journal of Essential Oil Bearing Plants. 20(3):601-609. doi:10.1080/0972060X.2017.1331143.